Submandibular gland biopsies may provide accurate diagnosis of early Parkinson's disease

In the future, transcutaneous submandibular gland biopsies may become a reliable and accurate new diagnostic test for Parkinson’s disease, especially early disease, according to results from researchers at Banner Sun Health Research Institute, Sun City, AZ, and the Mayo Clinic, Rochester, MN.

Their article, “Peripheral Synucleinopathy in Early Parkinson’s Disease: Submandibular Gland Needle Biopsy Findings,” has been recognized by Movement Disorders, the official journal of the International Parkinson and Movement Disorders Society as the “best original research article” of 2016.

“This was the first study demonstrating the value of testing a portion of the submandibular gland to diagnose a living person with early Parkinson's disease. Making a diagnosis in living patients is a big step forward in our effort to understand and better treat patients," said author Charles Adler, MD, PhD, a Mayo Clinic neurologist.

Diagnosis of Parkinson’s disease currently depends on a combination of the patient’s medical history, signs and symptom review, neurological exam, and ruling out other possible conditions, but up to 55% of patients may be misdiagnosed early on.

As part of the study, Dr. Adler and colleagues biopsied one submandibular gland in 25 Mayo Clinic patients with Parkinson’s disease, and 10 people without. Mayo Clinic otorhinolaryngologists Michael Hinni, MD, and David Lott, MD, performed the in-office procedures.

These researchers had previously demonstrated that this biopsy detected the abnormal Parkinson’s protein in 9 of 12 patients with advanced disease.

Here, the biopsied tissues were tested for evidence of the abnormal Parkinson’s protein by co-author and neuropathologist, Thomas Beach, MD, PhD, of Banner Sun Health Research Institute. He detected the protein in 14 of the 19 patients with enough tissue taken for analysis.

"This [submandibular gland biopsy] procedure will very likely provide a much more accurate diagnosis of early Parkinson's disease than what is now available," said Dr. Beach. "One of the greatest potential impacts of this finding is on clinical trials, as, at the present time, some patients entered into Parkinson's clinical trials do not necessarily have Parkinson's disease. And this is a big impediment to testing new therapies."

Similar studies, including the S4 study, are currently being performed in both the US and Canada. Researchers of the S4 study, specifically, will seek to compare submandibular gland needle biopsy with colon and skin biopsies in patients with Parkinson’s disease.

"This study provides the first direct evidence for the use of submandibular gland biopsies as a diagnostic test for living patients with early Parkinson's disease. This finding in patients with early Parkinson’s disease may be of great use, since accuracy of diagnosis in patients with early disease is not nearly as good as in those having the disease for more than five years,” concluded Dr. Adler.

This study was funded by the Michael J. Fox Foundation for Parkinson’s Research.